YDKG    #MAC  SHCLOSE   
 YF56    #   
 YFJQ    #STR  %A
 YG4B          LDX   0  %A               [IF %A PRESENT  
 YGJ2    #STR  %B
 YH3L          LDX   1  %B               [IF %B PRESENT  
 YHH=          '171  0  11   
 YJ2W          BNG   0  %C               [^ IF FAILED
 YJGG    #NOR